setValue: forUndefinedKey:]: this class is not key value coding-compliant for the

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ setValue: forUndefinedKey:]:. This class is not key value coding-compliant for the key datePicker'

Just a run on the explosion of this fault, the following is the code

http://files.cnblogs.com/itgiant/Pickers.zip

Reply:
ib created problems, not look, but it is recommended to use less ib, if you want to use, the corresponding IBoutlet also connected.
Reply:
1 determine IB problem.
2 you follow a tutorial tutorials you may not see very carefully, missing part.
3 how to use IB, you are not very clear, it is recommended to see more information online, what is meant by a variety of connections.
4 Your question appears on TabBarController settings.
Your first tabItem bindings should be DataPickerViewController instead UIViewController
(No datePicker UIViewController this property, so there will be an error).

You re-set it, on the right.